Thread-tension mechanism for sewing machines



June 4, 1929. M. KOHLER THREAD TENSION MECHANISM FOR SEWING MACHINES 2 Sheets-Sheet Filed Feb. 12, 1927 I INVENTOR I M Kdevpfl June 4, 1929.; M, KOHLER v 1,715,371

THREAD TENSION MECHANISM FOR SEWING MACHINES Filed Feb. 12, 1927 2 Sheets-Sheet 2* fig ATTORNEY Patented June 4, 1929.

' unirso stares The MAX KHLER, ,OF LIMBACH, GEBEANY.

Application filed February 12, 1927. Serial No. 167,628.

presentinvention relates to an improvement in sewing machines and more particularly to the mechanism for maintaining predetermined conditions of tension on the thread or threads used in said machines. One

' object of the present provide adapted invention has been to tension mechanism partlcularly for use on a sewmg machlne of the over-seaming type in which separate threads are used,

needle.

one for the looper and one for the It is also an object of the present invention to provide a tension mechanism from which spring control has been elimi-. nated and in which the desired degree 0 'tautness or looseness of the thread with re spect to the needle and looper will be af-- forded guiding agencies. invention has seaming machine means by operation of positively actuated been to provide in an overtension mechanism by of which the tension on the looper and needle threads respectively will be properly balanced and related to permit the mostrapid and efiective operation ofy said looper and needle.

One embodiment of my invention is illustrated in the drawings accompanying the present specification and in wh1ch front view with portions of shown in vertical section, and

Figure 2, a side view with casing portions of the broken away and interior 'portions shown In vertical section.

As indicated in thedrawings,

a preferred form of my improved tensioning mechanism is associated with a sewing known thread needle 2 and the looper 7 machine of well typeand including a looper'l and a mounted on carriers 3 and 4 reboth of which-aredriven from drivingshaft 5 by any suitable shown. thread 7 engage the 6 and a looper 1 respectively and,

in normal operation of the feed mechanismare withdrawn from suitable supporting means of any well known type, conveniently mounted on the framework of the machine or otherwise, it being deemed unnecessary to show the same.

The tension of both threads 6 and 7 is controlled to thread 6, guides 8 by similarmeans. For example, as

the web thereof engages fixe and 9 between which is positioned a frictlon guide 10, said guides being confaces of cam 18 A. further object of they slot whereby the extent of move A" needle such as spools,

veniently mounted on a bracket 11, which also supports guides 12, 13 and 14, corresponding respectively to the guides 8, 9 and 10 positioned to operate on thread 7 A .thread conduit. 15 extends through the front Between said conduit 15 and the fixed guide 9 are positioned spaced guides 16-and 17 having thread receiving recesses therein.

cam or take up 18 mounted on shaft 19 is grooved peripherally to form spaced pef ri'pheral thread engaging surfaces and 1s positioned to rotate between said spaced guides 16 and 17. A fixed guide 20 has one end extending between thethread engaging surand is provided with a thread guiding ment of the thread in the direction of rotation of the cam is eifectively limited.

The shaft 19 also carries a cam or take up 21 positioned between spaced guides 22 and 23. A slotted guide 24 is positioned with its slotted end projecting into the groove of the cam 21 and serves a purpose with respect to thread 7 similar to that served by the guide 20 with respect to thread6.

A spur gear 25 is mounted on shaft 19, being actuated from the driving shaft 5 by any suitable connection such, for example, as a shaft 26 having a pinion 27 engaging the gear 25 and the pinion 28 engaging agear 29 mounted on shaft 5. Motion ofrotation is imparted to shaft 5 by any suitable means, such as a belt connected to the fly wheel 30 and not shown.

In operation the looper 1 is given a combined reciprocatory and oscillating movement common to machines. of the type described while the needle 2 is given a-reciprocatory movement, all movements preferably being taken from shaft 5. The thread with- T oFFicE, I

to the end of the needle so d that the looper may engage properly, these considerations'being well understood by per- I sons skilled in the art. To afford a basic refixed between the spaced thread guides 16 and 17 and 22 and 23 respectively. It will be apparent that cams 18 and 21 during a.

portion of their rotation tend to retard or prevent the formation of slack in their respective threads whereas other parts of said cams tend to release said threads so that a greater looseness or slackness thereofwill be available for the loop forming operation.

It is believed that the tension mechanism hereinabove described provides a positive thread tension control which is not only more effective in operation than well known forms of spring tension control, but alsoshows su perior results in that the thread tensioning means of both looper and needle are synchronized with. the thread withdrawing means, whereby accurate operation of machines of this type is more nearly accomplished.- Other advantages flowing from practicable applications 0 be apparent from a consideration of the details of construction of the embodiment described in the foregoing specifications and illustrated in the drawings.

I claim as my invention:

Looper and needle thread tensioning mechanism for sewing machines, comprising a main drive shaft, a cam shaft operatively connected therewith, a set of spaced thread guides for the looperthread, a set of spaced thread guides for the needle thread, a pair of take up cams on said cam shaft, one of said cams being positioned to rotate across the path of said 100 or thread between said looper thread gui es, and the other cam being positioned to rotate across the path of said needle thread between "said" needle thread guides.

Intestimony whereof, I have signed my my inventlon will name tothis specification this 27th day of J anuary, 1927.

MAX KoHLER. 

